"Well" is normally used to qualify participle, i.e. an adjectival form of a verb, to describe the way in which something has been done: "well pleased", "well qualified", "well trousered, sir!". Although it qualifies an adjective in "well-nigh", this is an almost archaic expression, and shouldn't be used as an authority to construct combinations such as "well good", "well hard" or the like. It's a solecism, like "can't hardly" or the UK English "I've got" (in the sense of "I have", rather than "I have acquired"); and however popular it may be in colloquial speech, it's Bad Grammar. Don't let that put you off saying it, however, if that's how they talk round your way (and you don't find it objectionable yourself); but don't use it in your CV (resumé)!

BTW, "well good" is a tautology, but there's no reason why it shouldn't be deliberately employed as a rhetorical device, in the same way I say "you ... yourself" in the previous paragraph.

Hope that clears things up!

Steve