I saw this for the first time in something recent: "just wed".
I wonder how and when it is used (BrE only, under certain conditions). Does it mean exactly the same as "married"?
It's just one of those English things where there's a choice between Saxon-German or Norman-Latin words.
Wed is Germanic, meaning to wager/bet/promise; to marry comes from the Latin.
Both "just married" and "just wed" mean the same thing.
In my experience, I have seen "just married" more than "just wed." A Google Ngram confirms the usage of just married as more frequent:
Perhaps the shorter phrase was used to fit on the license plate.
You will also see "newlyweds" to refer to people who have just been married.