Have you tried dusting the wet food with a topper, like freeze-dried meat treats? Not sure if you can get the new Orijen freeze-dried treats, but they come in a vast array of flavours (from duck to beef to lamb, etc) and my cats go nuts for them. I just crumble them on top of any food they start getting picky with and it encourages them to eat more.
What brand and flavours of canned do you feed? How often do you rotate the flavours?
"To close your eyes will not ease another's pain." ~ Chinese Proverb
“We must not refuse to see with our eyes what they must endure with their bodies.” ~ Gretchen Wyler