Mod that replaces textures.

Is it possible to import textures from World of Warcraft into Heroes of Might and Magic V?

Yes and no. It depends on what you mean. If you simply place a texture on a model, then no. It will result in something incomprehensible due to mismatched UV maps. However, you can manually overlay one texture onto another, making the necessary adjustments, distorting it as needed, etc., in Photoshop. However, it may turn out that it is easier to adjust the existing texture, copying only those sections where it is not possible to achieve similarity through adjustments.