See if uvs, material ids etc are all imported into unreal correctly. Just make some material, create instance then apply it to imported mesh in content browser.
Not sure about houdini, but yes you should create one MASTER material in unreal. Add parameters for textures like diffuse, normal, etc. Then create instanced out of that master, and apply instances with correct textures.
Importing materials (when it works) will just create separate material for each piece. And this is not optimal, as instanced materials share same material in shader, so they are a bit easier on rendering.