Yes the white worms dietary issue was that previously we've been warned that they are too fatty for frequent feedings. I have kept them a few times but the cultures always died. I had grindals on scouring pads from Bilbo that I couldn't keep alive and later got some on old potting mix that also disappeared. All I have now are the ones that I find easy to keep - black worms, micro worms, daphnia and mosquito larvae.
Joe, if you want pond bugs you could set up something like my bugtopia pond. What likes to live in there will be what you end up with, I've tried transplanting various bugs from externally sourced places and in the end only the daphnia were the main colony. There are no doubt other microscopic bugs, snails, bloodworms etc, but you can't plan on keeping micro-bugs if the situation isn't right for them.