Mixing metals: wear and tear

[laine]

So I know platinum next to gold is a no-no, as the platinum will wear down the gold. What about other metals like:
palladuim
titanium
tungsten
stainless steel
sterling silver

Will platinum wear on these? Will they wear on platinum? What about with gold? What about wearing these "alternative" metals together? What is ok and what isn''t?

Thanks in advance for any info on all this.