UV mappings are the way to go then, that way you don’t have to create new materials for different parts.
Also, in your test file you are using picture material. It is better to create a PBR material instead, so that you can actually control on what channel the texture goes - although the mapping channel 1 should be good enough.
@BrianJ has videos on uv mapping that should help you a lot.
edit: here a couple in an older post Change Texture/material orientation on a surface? - #7 by BrianJ