Good old Shakespeare can get away with anything. Or maybe it’s Polonius who gets away with stuff. Either way – “Well” be with you?!? Well is suddenly a noun?
Or is “well” acting like an adverb, qualifying how to be? In any case no one could say this now. Or maybe it’s meant to be clunky? I mean, we know what he means. It’s a formality, a greeting, a wishing for wellness to gentlemen. It could be Rosencrantz and Guildenstern and maybe Hamlet, too or it could be some gentlemen he’s bidding goodbye. A busy prime minister version of Polonius wouldn’t have time to greet some gentlemen and then stand around while Hamlet and Rosencrantz talk about him. Unless Hamlet’s playing a power game here, stealing away the attention of his friends, leaving Polonius waiting while he talks about him. That scenario is kind of a dick move on Hamlet’s part. And sometimes Hamlet can be a real dick. And so can Polonius. It just depends on the production.