Probably the top museum in Lima is the Museo Arqueologico Rafael Larco Herrera.  Privately owned, it houses 45,000 pieces which include ceramics, textiles, and jewelry.  The focus is on pre-Columbian art, particulary the Moche Dynasty which is celebrated for their erotic ceramics.  There is an entire wing dedicated to the erotic art which is rather explicit.  We bought a replica of one of the pieces - so ask to see it when you visit us.