It is a lot for a 150G, once they are all full grown. Uaru are social fish, but keeping them in a pair is usually just fine. If they are a good size, then uaru usually adapt very well to being the only one also.
Only get a pair of sevs if they are a known pair. In a 150G, the chances are that if you just put in largish male and female sevs, they will more likely fight than pair up.
Personally I'd go for 2 x uaru & one sev.
3 x jurupari (or whatever species you actually get), is a bad number and you are very likely to get a very picked on 3rd fish. The other two may or may not get on well either. I know it's not usually recommended around here but I've always found that a singelton jurupari gets on very well in a community cichlid tank. Otherwise, get at least 5 to spread bickering. And they get to be big fish so 5 is a LOT of biomass to go with the other fish in a 150G.
Just so you can get an idea of what might work, in my 150G I have 2 x uaru, 1 x sev, 1 x angelfish, 1 x moonlight gourami, 1 x tanganyikan spiny eel and a few other platies and bleeding heart tetras. That works really well, and I would not want to put any more fish load in there personally.