Wicket and Play are two very different types of frameworks.
Play is a MVC framework which you probably will feel familiar with coming from Django. Like Django, it offers more than just the web bits and provides a JPA based ORM framework, scaffolding tools and probably a lot more (I have no practical experience with it). They have a great tutorial on their site, and you'll probably see the Django similarities there.
Wicket is a component oriented framework (like JSF and Tapestry) and focuses heavily on object oriented design. It's also MVC, per se, but pages are usually built by composing self-contained and reusable components (View and Controller, pluggable Models). These components can be extended by standard inheritance and composition and markup is very cleanly separated from code and easily modified.
Wicket can manage event callbacks and state automatically, so that you don't have to think urls at all, no matter how complex your page is. A quick example for a clickable button that goes a away when it's clicked (very useful):
// In a page constructor
add(new Link("link") {
public void onClick() {
setVisible(false);
}
});
I want to emphasize that you don't have to use server-side state, and that it's quite possible to use Wicket as a "normal" MVC framework if you want to (and yes, it's easy to get pretty urls).
The Wicket project focuses only on the core web framework and there are no extra "niceties" such as special ORM support or scaffolding. I personally agree with the Wicket project's philosophy here, but for new developers coming to the framework, doing "simple" stuff such as a sortable and pageable table can be a bit daunting as pre-built components are a bit scarce. The learning and productivity curve for Wicket can be a bit steep, but the upside is that once you've made components (and "behaviours" - longer story) that fit your needs, they are extremely reusable.
Although I personally love Wicket, I have a hunch that you probably will be best off with Play. Your question indicates that you want a "Django" with access to Java libs, and in that case I think Play (or some other Java MVC) is the safe choice. On the other hand, maybe you've been using Django because you didn't know how incredibly powerful Wicket is. ;) If you give some more info on your project, we'll be able to give a more qualified response.
As a side-node: As Play is not very mainstream (at least for now), I'd also consider Grails which has strong commercial backing and even more out-of-the-box modules.