Actually you can do this, but it is more a workaround than a really nice solution.
ion-refresher components can only be used in ion-content.
So you are able to put another ion-content in your page.
<ion-content padding>
<div>
<!-- Your other content -->
</div>
<!-- Additional ion-content -->
<ion-content>
<!-- Your inline ion-refresher -->
<ion-refresher></ion-refresher>
</ion-content>
</ion-content>
You need to put every ion-refresher into a new ion-content, because the ion-refresher component will be put at the end of the scroll-content container, that is generated in ion-content.
Just note, that you wont be able to use a full page ion-refresher with an in page ion-refresher, because both will be executed, when you try to pull the in page ion-refresher:
<ion-content padding>
<ion-refresher></ion-refresher>
<!-- Your other content -->
<ion-content>
<ion-refresher></ion-refresher>
</ion-content>
</ion-content>