Shower curtain rail joint inserts

[DIYspanner]

Its an over the bath square shower curtain rail. An old Wilko brand product.

It has inserts that reinforce the rail joints but they're all broken so I'm trying to source some fluted bar (if that's what its called) to repair the joints. The bar fits into oval tubes 9mm x 12mm. The photo shows the old stuff.
What product name should I be looking for?

 

[Wayners]

Make one.
12mm round dowel from B&Q is £3.27.
Knife and sandpaper you could get that to 9mm x12mm

 

[DIYspanner]

Having considered the application, some reinforced plastic pipe, about 11mm o/d, nipped and pushed in, will be suitable.