I have heard the same. There is a cheap AirTex and an "OEM" quality one. To me, that is just plain silly of any manufacturer. I myself installed an AC Delco because of all recommendations. Nearly a year in and all is still well with it. I like to have a backup pump always on hand and it is a Gates. But at $16 USD from Amazon Warehouse "used like new", I figured why not.

 

I bought a Hella pump as I thought I might need it, it came with a gasket, but splurged extra on a LR gasket. There is a clear difference between it and the one that came with the pump. Haven’t fortunately needed them so far after all.