Hi far_777, welcome to the forums.
The characters have two sets of textures, Normal and Wounded. You just need to replace the "Wounded" textures with copies of the "Normal" textures. The textures are .bmp files, but they are stored in .mmp files for the game, so you will need to extract the bmps, replace the Wounded .bmp textures, and then compile a new mmp.
The player textures are stored in: