Not everyone wears their engagement rings all the time. When, after 16 years of marriage, the prongs on my [husband's great-aunt's] antique diamond engagement ring's setting needed repair for the second time, I decided it was time to finally get the ring I would have preferred all along, a ruby in a modern setting. In the meantime I wore just the wedding band-- and found that I was actually quite a bit more comfortable just wearing the band.
Now, rubies are not nearly as hard as diamonds and can develop scratches and worn facet edges over time. Wearing rings at night also causes abrasion on the prongs from rubbing against bedsheets-- and I expect it would also cause wear on your pearl. So when we found the ruby we wanted and had it set, I decided to only wear the ring when I go out for pleasurable activities. This reduces the wear and tear on the prongs and the stone, keeps it from getting clogged with grease and dirt every day (as my diamond used to be) and the biggest benefit is that I notice it and enjoy it more. Things you see all the time fall into your blind spot eventually, but I really notice and appreciate my ruby more than I ever did the diamond ring before it.
So I say, go ahead and get the pearl ring, but consider not wearing it constantly. Solid nacre is a good idea (or be prepared to replace it periodically if you really want a South Sea pearl)