wear down vs exhaust

wear down is not a noun while exhaust is a noun.

Word	Noun	Adjective	Verb	Adverb
wear down	No	No	Yes	No
exhaust	Yes	No	Yes	No

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

Other hyponyms of wear down include beat, tucker, tucker out, wash up, overfatigue, overtire, overweary.

wear down (noun)	exhaust (noun)
	system consisting of the parts of an engine through which burned gases or steam are discharged
	gases ejected from an engine as waste products

wear down (verb)	exhaust (verb)
exhaust or get tired through overuse or great strain or stress	wear out completely
deteriorate through use or stress	eliminate (a substance)
	use up the whole supply of
	use up (resources or materials)
	deplete