The way I think about it: what's the text version of this? It's a list, with the status in brackets after the step name.
<ul>
<li><img src="blop.svg" alt="Step 1 (complete) - The long bit of text that describes step 1" /></li>
<li><img src="blop.svg" alt="Step 2 (complete) - The long bit of text that describes step 2" /></li>
<li><img src="bleep.svg" alt="Step 3 (current) - The long bit of text that describes step 3" /></li>
<li><img src="blorp.svg" alt="Step 4 - The long bit of text that describes step 4" /></li>
</ul>
Could also use aria-current="step" on the current step.