I will be going to a nursery soon. If I find some carnivorous plants there, would it be wise and safe for the plant to keep them inside, even though I don't keep insects in the house for them to eat? Or are they not indoor plants?
Graham is right. There are carnivorous plants that can be kept it inside. I wanted to add a few things, though. One is that some carnivorous plants will stay alive inside, but they might not do extremely well. They may need brighter light or higher humidity than your house provides. You can compensate if this is what your particular species requires by purchasing light bulbs that help to replicate daylight. You can look into all of that on a carnivorous plant (CP) forum. I've actually started looking into that aspect myself recently.
The other thing to consider is that some CP's need a dormant period or they will die. For instance, Venus Fly Traps and Sarracenia need to go dormant in the winter time. If you don't allow them to do this and keep them in a bright warm house all winter, then they'll grow and grow and then start getting weaker and weaker till they die. People who want to grow them inside often put them in the refrigerator or under their house for the winter. Just wrap the pot in plastic to help retain the moisture and check on it maybe once a month.
To be honest, though, they're very easy to grow out side most places. The like the bright light intensity and the hot summer and cold winters. If you live somewhere really cold, then I'd suggest you go on youtube and check out 'Brad's Greenhouse'. He lives in Canada and grows all kinds of orchids, CP's and air plants. While he does have a greenhouse, he also grows stuff outside and has many well made videos. Also, I tried to grow venus fly traps on and off for a few years with bad instructions from the internet. I found a book called 'Savage Garden' by Peter D'Amato. It had really good information and his method of growing was not only much easier for me to do, basically having to keep a water tray full, but the plants went gangbusters. The only problem I had with the water tray method was that the dogs, who had clean water 3' away, insist on drinking from my plant water trays. Good luck growing your CP's.
Carnivorous Plants like full sun generally though you could place your plant on a window sill with high levels of solar insolation if wanting to keep as a house plant. They live in nutrient poor boggy soils so you are going to need to water them frequently with distilled or rain water in summer. You can feed them freeze dried insects once or twice a month and these can be purchased from pet shops.