Ken, I got those inserts at my local Ace hardware store. They were in one of those little boxes of odds and ends and special 'used once in a lifetime' doo dads. The particular box where I found them was marked as 'Furniture Parts and Hardware' or something of that nature. I just remember that it was furniture related.
If you go looking for them at Home Depot you probably will not find them and the guy at my local HD store looked at me like I was from the planet Zorcon (how did he know?
) when I asked about them. I always knew there was a good reason that I like my local small town hardware store!
McMaster-Carr also carries the inserts I used and you can find them here in bags of 50 for about $9 depending on size:
http://www.mcmaster.com/#standard-threaded-inserts/=zl1l4o