If the manufacturer of one or both components markets either or both of these components as able to be assembled to comprise the patented innovation, the patent holder can sue that manufacturer for inducement of patent infringement, because the manufacturer is directly informing the buyer to purchase the component(s) to then assemble the separate components to have the buyer infringe the patent. Even if the manufacturer does not actively advertise such combination to achieve the patented innovation, merely pointing out in, say, engineering-design manuals is enough of a threshold to cross to prove inducement. Sometimes even lower thresholds might apply in wink-&-a-nod-esque situations, as long as the implication to infringe the patent is in the gist of various communications taken as a whole over time.
Please study Power Integrations, Inc. v. Fairchild Semiconductor Int’l, Inc. in the USA's Federal Circuit for one of the most-recent precedents on the finer points of inducing a 3rd party to infringe a patent. Obviously, that case refers to multiple prior precedents that it itself studies within the ruling.
In addition to the linked case ruling itself, please perform a Bing or Google search for “Power Integrations, Inc. v. Fairchild Semiconductor” as you will find numerous filings from the plaintiff & defendant as well as numerous legal-forum & legal-firm discussions of this case.