A friend sent me this link for a bedwetting product called "Rip-N-Go". It's a detachable, washable sheet set that protects your mattress and sheets from bedwetting.
Unfortunately, it wouldn't work for Alex. Anything that he can get his hands on and remove doesn't last long in our house. But I could see this being very helpful for children who are less destructive.
The product was created by a local Ottawa mom who was frustrated by having to replace the entire fitted sheet when her baby had a leaky diaper.