This sounds simplistic, but have you given the dog a scolding with a NO command?
Try this, take three OLD bumpers and one NEW one. Toss out an OLD bumper 5 yards in front of you with the dog steady at your side. Let the dog sit for a few seconds, staring at the bumper, then send it for the retrieve. As soon as the dog gets the OLD bumper in its' mouth, command HERE. Praise upon delivery. Repeat this three times in rapid succession with the OLD bumpers. Hopefully the dog performs the first three well, and in quick succession. For the fourth, throw out the NEW bumper. As soon as the dog gets its' mouth ON the bumer with wings, command HERE. It the dog doesn't comply, take it away and give a stern NO, then repeat HERE. Start over with the three OLD ones.
At some point in the process the dog should realize that the NEW bumper isn't a toy and that you expect them to retrieve it just like they would any other. It might take time, and the 'newness' of the NEW bumper & wings might have to wear off, but it eventually will.
You might also throw in a long lead on the dog during the retrieves so that you can tug it back in when it wants to lay down and chew.
That is the nice approach...
I'm assuming the dog isn't Force Fetched otherwise this wouldn't be a problem. This is a big reason why trainers use the Force Fetch on retrievers. It turns the retrieve from something THEY want to do into something YOU want them to do. I won't go into a big tirade or hard sell on the Force Fetch, instead I'll tell you how I would correct it on my dog. If this was my dog, who has been Force Fetched, it would go like this.
I throw out the NEW bumper
He lays down with it and starts chewing on it
I give the stern NO, followed immediately by what I want him to do, which would be FETCH
At that point he says to himself "Oh, your serious", and brings it to me
"I'll start spending less time with my dog and more with my wife when she starts fetching ducks for me"