Wife will not bathe.

You can hire an aide to come to your house and bathe her. Sometimes professionals have better luck in persuading. They’re trained in health care.

DEdave, have you tried just telling(and not asking)your wife that it's time to shower/bathe? Often you will have better luck when you just tell them.
And you may have to assist her in and out and even washing her her up, as her brain is broken and she no longer remembers how to do it, plus she may be afraid of falling.
My late husband had vascular dementia, plus was a fall risk, and I had to help him in the shower(we were fortunate to have a walk-in shower in our master bath)have him sit on the shower chair and then I myself would wash him up real good to make sure that he was good and clean, and then I helped him out and would help dry him off.
So make sure that your shower/bathtub is safe with a slip proof mat in it, shower chair of some sort, and has grab bars so your wife feels safe in it.
And if all else fails, you can hire aides to come in to assist her with bathing, as often someone with dementia will listen to an outsider much better that a loved one.
I wish you the very best as you continue on this road with your wife.

If this is a new behavior it might be appropriate to talk to her doctor. Otherwise, is there someone who could gently encourage or help her do so?