I hope that this is of some help. I am British married to a Peruvian, and I went to the Maison de Sante, and was signed onto their system with no problem at all. They have clinics in San Isidro, and Miraflores,and other parts in Lima. The cost per month for my wife and I, is $49. We are not able to claim for the first 3 months, and thereafter we are then covered. 90% of tablets/meds are covered, and also payments for their clinics. Because we only stay in Peru for periods of up to 3 months, we keep the fees going by payments on the internet. They are efficient.
P.S. At the initial interview/examination they do stress that pre-existing conditions were not covered,which I believe is normal practice anywhere.