Workflow base on `item` type : product, asset, service

I want to make a workflow for purchase order for example, but with some condition on type of items doctype
let say, I want to

if item is asset type then assign to person_A to check or validate or approval
if item is product_item assign to person_B to check or validate or approval
else

Could you please guide me or give me some tip about this implementation.

Thanks