std::map::insert takes a single argument: the key-value pair, so you would need to use:
mapa.insert(std::make_pair(p1, "Manzana"));
You should use std::string instead of C strings in your types. As it is now, you will likely not get the results you expect because looking up values in the map will be done by comparing pointers, not by comparing strings.
If you really want to use C strings (which, again, you shouldn’t), then you need to use const char* instead of char* in your types.
And in general How can I use any kind of structure (objects, structs, etc) as a key in a map?
You need to overload operator< for the key type or use a custom comparator.