Yes, you just need to change the war3map.shd, war3map.wpm and war3map.w3e files.
war3map.shd -> Shadow map. As long as it is the correct size it will work. Some people even say maps without them still work but with a warning.
war3map.wpm -> The pathing map. It is sort of a bitmap file representing pathability of the map.
war3map.w3e -> Mesh file. This represents the actual terrain in the map (water, tiles, height etc).
Do be aware that map objects (doodads, destructible, units etc) are other files completely.