...pearls and bezels on ebay—both new and used. However, you've got to be careful so as to avoid purchasing aftermarket parts being sold as OEM Rolex parts. A VRF member may also have what you need for sale, so check the listings.
I've never heard of anyone repairing a Sub bezel (they're generally replaced when badly damaged), but it may be possible. Unless someone with experience with that type of repair chimes in, I'd find a local watchmaker with a Rolex parts account and take it to him. He'll likely recommend replacing it. On the other hand, unless the business side is severely damaged, I'd probably just reinstall it (presuming it hasn't been bent out of shape)—with or without the pearl—and consider it added character.