The Mazda/Mustang internal WP design is nuts. I think regular check of coolant level and oil level and oil appearance is one way to monitor internal seepage However, the weep hole is designed to channel WP seal leakage toward the outside where it should be readily visible that the pump is failing.
A total failure of the pump can internally leak but I'm not sure how many of those have occurred causing engine failure.
The chain drive design and location of the pump assures replacement will be expensive if you outsource it to local shop. Or mentally exhaustive if you try to undertake the task yourself. Additional cost is often incurred to replace other hardware that's found worn out when the timing cover is removed to replace the pump.
I don't think most buyers of the V6 think of this maintenance task before buying a 3.7.
And to answer your question, I don't know any preventative actions or periodic maintenance that can prevent the water pump from failing.
2012 Mustang GT, Roush 2300 Black
2006 Mustang V6 Manual Legend Lime Sold
2019 Charger Scat Pack White
2016 Jeep Willys Silver Vin 060 GBNF
2016 Jeep Willys Silver Vin 059 Sold