I've actually never come across a GMB, but I found out that some Audi models use them. I didn't know it was a Japanese brand. HEPU seems pretty popular. I also know that there is an Italian water pupm for the Audi, and it has a plastic impeller that likes to get loose on its shaft, which results in silent water pump failure.
I'm not sure, but the above shown water pump came most likely as part of "timing belt kit" that is available from an online parts store. Because my timing belt is soon due, I'm interested in finding out about the various brand parts that come with the kits that I see.