I bought a new Jebao marine DC pump, from a quality lfs, for the aquarium I set up in April of this year. Within weeks I was seeing rust on the exposed 'stainless' steel screws and nuts. Even then, I thought it was probably just superficial. Then I saw rust starting to work it's way out of a seam between two parts of the volute/case. About this time, Triton Labs tells me my water is quite high in TIN, a major source of which is, you guessed it, rusting metal.
So, that DC pump wasn't so great. I've since replaced it with a Reef Octo VarioS-6 DC pump, which is Apex-ready and also includes an optional float switch which plugs directly into the pump's variable speed controller. Seems much better built than the Jebao pump; for one thing, no exposed metal parts. Super quiet, with higher volume flow than the other one. I guess we'll see about longevity.