If you wanna check exchange rates, you can use cuantoestaeldolar.pe. Check the row that says "Cambistas", and then "Compra" column. That's how many PEN you get per USD.
Exchanging CAD>PEN would be difficult, as mentioned above. I second the suggestion of doing CAD>USD up north, and then USD>PEN here.
Also, several friends of mine prefer to just withdraw PEN from ATMs. They say the exchange rate is decent and they avoid the hassle of exchanging the money. Just a matter of checking with your bank - you may even have fees for that.