I used successful the Amazon SeaFlo Pressure pumps on my boats and agriculture irrigation system on my truck and they do very well despite the lower price.
This, you need pressure for washdown but less pressure and more flow for the livewell, i had the same system (1 pump for two purposes) on my BW 23 and it worked as supposed.
If you want the same then as suggested, bring the pump to WM and get a new one
If you want to build a better system then use two pumps as Hookup1 suggested, but in this case you should install a second thru-hull for the livewell pump what would be a overkill.
The one pump for two purposes work if designed correctly, as i wrote i had that for many years and it worked as supposed but BW had a kind of grille in front the outlet inside the livewell to reduce water movement to avoid that bait fish get washed around.
Chris