I have a friend who is legal in the US but is from Peru. He has 2 young nephews who he wants to bring to the US to take them to Disney World. What

The children will need to apply for B2 visitor visas. The application is submitted online and the kids will need to appear for an interview with their parents. They will likely need documentation from the parents authorizing the trip and a letter from him staring he will be caring for them. You can read more about visitor visas at  http://myattorneyusa.com/travel-visas.