Most espresso machines I come across/see pictures of these days seem to use
Fluid-O-Tech. According to
ChrisCoffee, they switched to F-O-T after finding that Procon's quality diminished after they moved from the US. I have had superb experiences ordering parts and getting pumps serviced directly from Fluid-O-Tech; the US branch seems to have highly competitive prices (say, about $100 for a standard rotary pump head, vs. $140-150 from your average espresso machine service place), and they stand behind their products in my experience—I had some scale forming on one of my pumps out the weeping holes behind the shaft bearing after < 1 year of owning it, and they refurbished the pump for me for no charge.
I can't say anything for Hydropure, as I've never owned or seen one. Their
website looks and sounds like a nightmare from the 1990s. Looks like Espressoparts NW carries a pump from them, so they might be the people to ask about it if you can't find anyone here to give info on them.