wear away vs rub down

wear away and rub down both are verbs.

Word	Noun	Adjective	Verb	Adverb
wear away	No	No	Yes	No
rub down	No	No	Yes	No

As verbs, rub down is a hyponym of wear away; that is, rub down is a word with a more specific, narrower meaning than wear away:

Other hyponyms of wear away include abrade, abrase, corrade, rub off.

wear away (verb)	rub down (verb)
become ground down or deteriorate	wear away
diminish, as by friction	manually manipulate (someone's body), usually for medicinal or relaxation purposes
cut away in small pieces