Desde un <p:button>

Cambiar el valor de un parametro desde un commandButton

PrimeFaces already incorporates jQuery UI, you shouldn't bundle it yourself. There is

p:button

component. Here is example on

Primefaces Showcase

. So for your case:

<p:button outcome="#{listadoUsuario.verUser(user.username)}" value="ver" icon="ui-icon-pencil"/>  
You can use
<f:param name="productId" value="10" />