If you’re looking for topographic maps of Peru, you’ll find an impressive series at the University of Texas Libraries website. The can find the relevant page here: Peru Topographic Maps 1:100,000.
The maps, which are all downloadable as PDFs, cover a number (but not all) of Peru’s major cities and immediate surroundings, as well as many smaller locations.
All of the maps are in 1:100,000 scale and include many natural and man-made features. They were originally created by the U.S. Defense Mapping Agency (Series J632) in the mid-1990s, so be aware that some man-made elements may no longer exist.
Trekkers might find many of the maps insufficient for their needs, but at least good enough for the planning stages.